The shift register may operate as a gate drive circuit of a display device to sequentially supply the gate lines with a gate scan signal to turn on the transistors in each row of pixels to allow writing of a data signal to each pixel.
In order to fully turn on the transistors, the high level of the gate scan signal generally needs to reach 25 V or more. Due to the self-boosting effect of the storage capacitor in the shift register, the potential at some internal nodes of the shift register may be even higher, e.g., more than double the high level of the gate scan signal (above 50 V). Such a high potential results in a large change in the characteristics of the transistors connected to these internal nodes, producing threshold voltage drift. If the display device operates under such conditions for a long time, the shift register becomes unstable, thus yielding degraded gate scanning signals.